This interpretation is practically supported by what the Romney camp itself has said about the ad. Romney advisers have proudly boasted that their dishonesty “worked,” because it secured more media attention for the ad and baited the Obama team into an all-out response, creating the impression of a head-to-head media showdown between Romney and the President. It’s only a tiny leap from there to the conclusion that the Romney camp saw the dishonesty itself as a way to prove to GOP primary voters that Romney will do whatever it takes to beat Obama. And if this is the game, then the Romney camp’s unrepentance in the face of widespread media condemnation only helps, signaling that Romney is willing to employ whatever tactics are necessary to end the Obama presidency even if it means bravely taking a sustained beating from the Obama-worshipping liberal media along the way.

If this interpretation is correct (about which I'm agnostic for the moment), I think Greg gets it right. It's not so much to show that Romney is willing to take heat from Obama, it's to show that he's contemptuous of criticism from the press. If there's anything the GOP base hates more than Obama, after all, it's the liberal media. Newt Gingrich has played on this hostility pretty effectively for months, and with Gingrich rising in the polls maybe Romney decided he needed to get into the act too.